In multi-thread condition, EnableProfiler can
be called after RecordEvent is constructed. In this
case, RecordEvent constructor will not init anything,
but RecordEvent destructor will do something since EnableProfiler
was called.
This PR fixes it.

* Fix the bug when a input variable of op is dispensable.

* Add HasInputs/Outputs interfaces to OperatorBase.

* Remove the unreferenced header file.